Runner System Design Calculator
Calculate runner diameter, length, and volume for balanced multi-cavity injection molds.
Inputs
oz
mm
mm
Results
Main Runner Diameter
5.25 mm
Sub-Runner Diameter4.2 mm
Gate-End Runner2.94 mm
Main Runner Length180 mm
Runner Volume6.39 cm³
Runner Weight6.71 g
Runner-to-Part Ratio5.6%
How to Use This Calculator
- Enter part weight (g), number of cavities, and maximum wall thickness (mm).
- Set flow length (mm) from sprue to gate and material viscosity class.
- Review recommended main runner diameter, sub-runner diameter, and gate-end runner diameter.
- Check runner volume relative to shot size — runner waste should typically be below 20% of shot weight.
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Related Calculators
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Estimate injection mold build cost from cavitation, material, part complexity, and features like side actions and hot runners.
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